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polypropylene?

Discussion in 'Body Jewelry' started by mike, Jul 30, 2013.

  1. mike

    mike Member

    anyone have any info about long term wearing of jewelry made from polypropylene? i have seen the propylux jewelry hear on painful pleasures. is this like acrylic? not in structure or makeup, what i mean is, bad for piercings but cheap and marketable so many manufacturers use it. through my own research and knowledge of the material, i believe it is autoclavable, mostly inert, low water absorption, heat stable, etc. it has much more in common with PTFE than acrylic but is much cheaper than PTFE. all desirable qualities. does anyone have any info that would suggest it could be a bad idea?

    the main reason i ask is because i'm a machinist and i have an overabundance of this material, enough to make several thousand pieces of large gauge jewelry. i have a hard time stretching; my skin is not very elastic. i have downsized considerably to 00g (as small as i can go) and want to re-stretch. using tape wraps to stretch is a pain in the butt. i would much prefer to take a bunch of this material i overstocked and machine a bunch of plugs in very close sizes, going up as small as 0.010" (about a quarter of a millimeter) increments.

    just wondering if anyone thinks i might regret this course of action later.
     
  2. dnd4evr

    dnd4evr Super Moderator Staff Member

    I doubt anything autoclavable is polypropylene. Most autoclave temperatures are above 120ºC and depending on the cycling can be as high as 135ºC (almost 280ºf). Heat distortion of polypropylene can start at 105ºC. The softening point for acrylic is 80ºC. Neither of these materials would be good candidates for an autoclave. Sterilization of plastics is usually done with Ethylene oxide (ETO).

    I have a posting here in the forum where I go into the FDA requirements on long term materials for use in breached surfaces. Any material in a fresh piercing should meet the requirements.

    Many plastics have a porous even though they can hold water. Bacteria and such can get into the gaps and cause problems. That why materials like Glass and metals are primarily used. PTFE is also very good depending on the grade of material.

    For personal use... be careful and aware of your body and monitor carefully and I would hope you could be ok, but I can not recommend it. Polypro may not machine very smooth and that can lead to crevices that could harbor unwanted "things". A quick flame treat (or heat gun) after machining should smooth over and seal the surface.

    Since you said you have a lot of this, I would not recommend trying to sell jewelry made of it. There may be liability issues.
     
  3. mike

    mike Member

    i was under the assumption autoclave temp was 121 C. melting point of polypropylene is about, 130 i believe. i'm aware deformation can occur prior to that. i know i've seen autoclave bags made from polypropylene before. it's been a while since i've shopped for those, maybe those are inferior/cheap bags compared to what is common now, i don't know. not trying to be argumentative or insinuate you are wrong, i believe you. just stating what i know i have seen in years past. i wouldn't have asked if i didn't value the input and i thank you for it.

    i have no intention of selling it, so liability is none of my concern. i just stated i had enough to make several thousand pieces to give you an idea as to the mass volume i have of this laying around. i don't intend on using it all for jewelry. i should have clarified.
    also, with slight attention to detail it can be machined to very fine finishes with no secondary finishing, especially turning simple shapes such as plugs. i wouldn't be much of a machinist if i didn't know how to achieve fine micro-finishes in a variety of materials. you'd never know it wasn't perfect without a profilometer or microscope (then again you'd be surprised the flaws you can find in anything, no matter how smooth, using those).

    i'm in no rush and think i will continue to research but unless i have further info on negative side effects/possible dangers, i think i will proceed further down the road with caution. listen to my body and turn back immediately if something doesn't seem right.

    again, all input is welcome and very much appreciated. thanks in advance.
     
  4. dnd4evr

    dnd4evr Super Moderator Staff Member

    You are welcome.

    By the way I am an engineer and I am currently working for a medical device manufacturer. My machining skills are no where near on par with yours and no insult was intended. I have a great respect for machinists since my father was a class A tool and die man for years. He made some pretty amazing things.

    For healed ears going through small stretches you are probably fine. I think it was important to express caution since there are those here who may not have the same level of experience who might try things without thinking and run into trouble.

    I once tried using bags for ETO sterilization in our autoclave and melted the film around my jewelry and pliers. What a mess. Not all autoclaves operate at 121. Ours has 3 temperature settings that vary the time, temperature and pressure. The setting we typically use is middle of the road. I never checked the material so perhaps it was polyethylene.

    At my previous job I worked for a company that made air quality monitoring and sampling equipment. We molded a filter cassette out of Bayblend which contained ABS and Polycarbonate. Some jackass customer (government agency) put the 2 halves together and ran them through a sterilizer. The pieces stretched out and fell apart. They tried to say we shipped them that way. Marketing just likes happy customers so I think they replaced them free, but they all went out with a note after that saying you can't steam sterilize the parts. It never happened again. Even if the parts weren't under stress the process of stress relief that occurs above the softening temperature may alter a parts physical dimensions so I would check them afterwards. Assuming the change is consistent you can just adjust the starting size to get what you want.
     
  5. mike

    mike Member

    didn't take any offense, i don't expect people to know my skill set.
    medical is something we have in common. i haven't done medical components in years but back when i was first learning my craft, i used to do a lot. it taught me to learn fast and be very comfortable with extremely small intricate work. there are a ton of people still walking around with pacemakers that i made parts of.

    have used autoclaves but don't have enough experience with different models, didn't know they went that hot.

    lol, yeah, HDPE might stand up to it, but any other grade of polyethylene definitely melts at that temp.

    i totally hear you about the stupidity of customers, especially government ones. i currently have numerous government customers (as well as armor manufacturers and independent certified test labs) that i work with in the specialty field of ballistic testing (everything from glasses, to helmets and vests, to tank armor, etc.).
     
  6. dnd4evr

    dnd4evr Super Moderator Staff Member

    We make pain management equipment. Catheters, needles, RF products and a few other items. Nothing implantable like a pacemaker.

    It had been a while since I last looked at our autoclave. It is an older unit and has 4 cycles available. It is our engineering R&D unit and does not get constant use. Two cycles are at 121ºC @ 128 kPa and 2 are 132ºC @ 210 kPa (the times vary). For anyone interested, here is a link to steam sterilization.

    http://www.csao.net/files/pdfs/70-2... Steri lization Cycles for Your Loads 309.pdf
     
  7. Andrea_L

    Andrea_L New Member

    Yo, just googled the same question and found this thread. Thought I'd add my bit:

    From working/studying in microbiology labs, I can say categorically that polypropylene (PP) is autoclavable at 121degC (the most common temperature used for sterilising equipment in bio labs). Our PP consumables soften at high temperature but do not deform at 121degC and the pressure we use (sorry I can't remember the pressure, but it's standard).

    I've known acquaintances to stretch with PP lab consumables (pipette tips and small vials) when the sizes were right... I found something that has the elusive 7 mm circumference, just what I wanted, so I decided to try it last night and it seemed to work well (?).

    PP is suitable for certain lab applications because proteins, bacteria and cells do not adhere well to it. Incidentally, they're properties I'm looking for in jewellery for freshly-stretched piercings.
     
  8. dnd4evr

    dnd4evr Super Moderator Staff Member

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    The pressure at 121ºC in the autoclave listed above is approx. 18PSI. There are various grades of PP and there are some that are suitable for an autoclave. I have even seen class VI grades of it.
     
    Last edited by a moderator: Aug 7, 2017

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